1. Field of the Invention
This invention relates to the fabrication of magnetic read/write heads that employ TAMR (thermally assisted magnetic recording) to enable writing on magnetic media having high coercivity and high magnetic anisotropy. More particularly, it relates to the use of a shock-protected laser to transfer the required thermal energy from the read/write head to the media.
2. Description of the Related Art
Magnetic recording at area data densities of between 1 and 10 Tera-bits per in2 involves the development of new magnetic recording media, new magnetic recording heads and, most importantly, a new magnetic recording scheme that can delay the onset of the so-called “superparamagnetic” effect. This latter effect is the thermal instability of the extremely small regions on which information must be recorded, in order to achieve the required data densities. A way of circumventing this thermal instability is to use magnetic recording media with high magnetic anisotropy and high coercivity that can still be written upon by the increasingly small write heads required for producing the high data density. This way of addressing the problem produces two conflicting requirements:
1. The need for a stronger writing field that is necessitated by the highly anisotropic and coercive magnetic media.
2. The need for a smaller write head of sufficient definition to produce the high areal write densities, which write heads, disadvantageously, produce a smaller field gradient and broader field profile.
Satisfying these requirements simultaneously may be a limiting factor in the further development of the present magnetic recording scheme used in state of the art hard-disk-drives (HDD). If that is the case, further increases in recording area density may not be achievable within those schemes. One way of addressing these conflicting requirements is by the use of assisted recording methodologies, notably thermally assisted magnetic recording, or TAMR.
The prior art forms of assisted recording methodologies being applied to the elimination of the above problem share a common feature: transferring energy into the magnetic recording system through the use of physical methods that are not directly related to the magnetic field produced by the write head. If an assisted recording scheme can produce a medium-property profile to enable low-field writing localized at the write field area, then even a weak write field can produce high data density recording because of the multiplicative effect of the spatial gradients of both the medium property profile and the write field. Many of these prior art assisted recording schemes involve deep sub-micron localized heating initiated by an optical beam.
The heating effect of TAMR works by raising the temperature of a small region of the magnetic medium to essentially its Curie temperature (TC), at which temperature both its coercivity and anisotropy are significantly reduced and magnetic writing becomes easier to produce within that region when the medium cools down.
In the following, we will address our attention to a particular implementation of TAMR, namely the transfer of electromagnetic energy to a small, sub-micron sized region of a magnetic medium through interaction of the magnetic medium with the near field of an edge plasmon excited by an optical frequency laser (“optical laser” for short). The transferred electromagnetic energy then causes the temperature of the medium to increase locally.
The edge plasmon may be excited in a small conducting plasmon antenna (PA) or in a plasmon generator (PG), typically approximately 200 nm in width that is incorporated within the read/write head structure. The source of optical excitation can be a laser diode, contained within the read/write head structure, or a laser source that is external to the read/write head structure. The external laser excites the near-field source through free-space coupling, whereas a slider mounted laser may direct its beam of optical radiation at the antenna through a means of intermediate transfer such as an optical waveguide (WG). As a result of the WG, the optical mode of the incident radiation couples to a plasmon mode in the PA or PG, whereby the optical energy is converted into plasmon energy, This plasmon energy is then focused by the PA or PG onto the medium, at which point the heating occurs. When the heated spot on the medium is correctly aligned with the magnetic field produced by the write head pole, TAMR is achieved.
Typically in the TAMR assembly the laser unit and associated optical elements as well, are mounted directly on the slider and extend beyond the normal slider and HGA (head gimbals assembly) geometry. In this exposed position, the laser unit becomes prone to damage during shock events. The following prior art all show lasers that are exposed to such shock-induced damage because of their mounting.    Rettner et al. (U.S. Pat. No. 7,289,422) describe a slider mounted laser.    Ito et al. (US Publ. Pat. Appl. 2010/0202256) also shows a slider mounted laser.    Olson et al. (US Publ. Pat. Appl. 2008/0068748 teaches that a laser may be mounted on a head carrier.